Preferred Stock Preferred Stock (Details) $ / shares in Units, $ in Thousands		3 Months Ended		12 Months Ended
	Jul. 15, 2019 shares	Mar. 31, 2019 USD ($)	Apr. 01, 2018 USD ($)	Dec. 31, 2016 USD ($) trading_day $ / shares shares
Class of Stock [Line Items]
Preferred stock dividends | $		$ 8,733	$ 8,733
Depository Shares
Class of Stock [Line Items]
Depository shares issued (in shares)				5,200,000
Interest in preferred stock per depository share				0.01
Six Point Seven Five Percentage Series B Mandatory Convertible Preferred Stock
Class of Stock [Line Items]
Percentage of issued shares				6.75%
Offering price per share (in usd per share) | $ / shares				$ 100
Threshold trading day period | trading_day				20
Proceeds from offering, net | $				$ 501,000
Six Point Seven Five Percentage Series B Mandatory Convertible Preferred Stock | Scenario, Forecast | Minimum
Class of Stock [Line Items]
Preferred stock converted in to common stock (in shares)	120.46
Number of common stock issued upon conversion (in shares)	6,200,000
Six Point Seven Five Percentage Series B Mandatory Convertible Preferred Stock | Scenario, Forecast | Maximum
Class of Stock [Line Items]
Preferred stock converted in to common stock (in shares)	132.50
Number of common stock issued upon conversion (in shares)	6,900,000